Capacitive coupling system for an antenna radiator, and antenna system

Abstract

A capacitive coupling system for an antenna radiator is disclosed. The system comprises a first signal line having a first signal line portion, and a second signal line having a second signal line portion and configured to be connected with an antenna radiator. The system comprises a capacitive coupling bridge formed of sheet metal and having a first and a second coupling portion, the coupling bridge being configured to arrange the second signal line in a predefined pose relative to the first signal line, the capacitive coupling bridge further configured to provide a first capacitive coupling between the first coupling portion and the first signal line portion, and to provide a second capacitive coupling between the second coupling portion and the second signal line portion to capacitively couple the first signal line to the second signal line.

Description

[0001] Capacitive coupling system for an antenna radiator, and antenna system

[0002] TECHNICAL FIELD

[0003] The present disclosure provides a capacitive coupling system for an antenna radiator, and an antenna system comprising the capacitive coupling system.

[0004] BACKGROUND

[0005] In order to emit an electromagnetic wave from an antenna radiator, said antenna radiator must be fed with a feed signal via a so-called feed line. Antenna arrays with multiple radiators may have multiple feed lines that are part of a feeding network. Dual-polarization radiators may also require multiple feed lines, each associated with a different polarization.

[0006] In some solutions, an antenna radiator is directly soldered to its feed line. Such soldering connections generally have the disadvantage that manufacturing costs are comparatively high. Furthermore, solder connections for different antenna radiators may differ from one another, especially if they are provided by a human labourer. This may lead to unwanted differences in the behaviour of similarly designed antenna radiators and can cause additional passive intermodulation. If the antenna radiator is to be directly soldered to the feed line, this also poses certain restrictions on the geometric arrangement of the antenna radiator relative to the feed line.

[0007] In other solutions, the feed line is split into two sections that are soldered to one another, with one of the sections being in direct electrical contact with an antenna radiator. Although this may increase flexibility in the geometric arrangement of the antenna radiator relative to the feed line, the general disadvantages of solder connections still apply to such a solution.

[0008] SUMMARY

[0009] There is a need for a technique that solves one or more of the above or other problems. According to a first aspect, a capacitive coupling system for an antenna radiator is provided. The system comprises a first signal line having a first signal line portion. The system further comprises a second signal line having a second signal line portion and configured to be connected with an antenna radiator. The system further comprises a capacitive coupling bridge formed of sheet metal and having a first and a second coupling portion. The coupling bridge is configured to arrange the second signal line in a predefined pose relative to the first signal line. The capacitive coupling bridge is further configured to provide a first capacitive coupling between the first coupling portion and the first signal line portion, and to provide a second capacitive coupling between the second coupling portion and the second signal line portion to capacitively couple the first signal line to the second signal line.

[0010] The first signal line may be electrically isolated from the second signal line. The first signal line and the second signal line may be (e.g., only) capacitively coupled to one another via the capacitive coupling bridge. The system may be configured such that a signal can be fed from the first signal line to the capacitive coupling bridge via the first capacitive coupling and from the capacitive coupling bridge to the second signal line via the second capacitive coupling. The signal may then be fed from the second signal line to the antenna radiator.

[0011] The first signal line may be arranged (e.g., entirely) in a first plane. The second signal line may be arranged (e.g., entirely) in a second plane. The second plane may be different from the first plane. The first plane may be parallel, oblique or perpendicular to the second plane.

[0012] At least one of the first coupling portion and the second coupling portion may be planar. For example, the first coupling portion and the second coupling portion are each planar and connected to one another via a bent portion of the sheet metal forming the capacitive coupling bridge.

[0013] The first coupling portion may extend longitudinally along a first axis. The second coupling portion may extend longitudinally along a second axis. The first axis may be different from the second axis. For example, the first axis may be parallel to the second axis. The first coupling portion may be offset from the second coupling portion, for example along at least one of the first axis and the second axis.

[0014] The first signal line may be associated with a first substrate. The second signal line may be associated with a second substrate. The second substrate may be separate from the first substrate. The capacitive coupling bridge may be configured to fix the first substrate relative to the second substrate.

[0015] The first signal line and the second signal line may be considered to form a signal line set. The system may comprise multiple signal line sets, each signal line set comprising or consisting of a first signal line and a second signal line. The system may comprise a separate capacitive coupling bridge for two or more or each of the signal line sets. Two or more or all of the first signal lines (e.g.zof the signal line sets) may be associated with a (e.g., the) first substrate, also referred to as first common substrate herein. Two or more of all of the second signal lines (e.g., of the signal line sets) may be associated with a (e.g., the) second substrate separate from the first substrate, also referred to as second common substrate herein. Each signal line set may (e.g., together with the capacitive coupling bridge coupling the first signal line and the second signal line of the same set) form (e.g., part of) a respective (e.g., symmetrical) feed line (e.g., for the antenna radiator).

[0016] Two of the second signal lines (e.g., forming a balanced feed and / or associated with a same dipole of the radiator) may be arranged on opposite surfaces of the second substrate (e.g., in a mirror-symmetric manner). In this case, the second substrate may not comprise a ground layer (e.g., a conductive layer electrically connected to ground, for example via an additional capacitive coupling bridge), so it may be referred to as ground-free second substrate. Alternatively, the two of the second signal lines may be arranged (e.g., at least partially parallel to one another) on a same surface of the second substrate. In this case, the second substrate may comprise a ground layer (e.g., extending in parallel to one or both surfaces of the second substrate), so it may be referred to as grounded second substrate.

[0017] Two of the first signal lines (e.g., forming a balanced feed and / or associated with a same dipole of the radiator) may be arranged on opposite surfaces of the first substrate (e.g., in a mirror-symmetric manner). In this case, the first substrate may not comprise a ground layer, so it may be referred to as ground-free first substrate. Alternatively, the two of the first signal lines may be arranged (e.g., at least partially parallel to one another) on a same surface of the first substrate. In this case, the first substrate may comprise a ground layer (e.g., extending in parallel to one or both surfaces of the first substrate), so it may be referred to as grounded first substrate. At least one of the signal lines may be arranged on its associated substrate. At least two of the second signal lines may be arranged on opposite surfaces of the second substrate. At least two of the second signal lines may be arranged on a same surface of the second substrate. Alternatively, or in addition, at least two of the first signal lines may be arranged on a same surface of the first substrate. At least two of the first signal lines may be arranged on different surfaces of the first substrate. At least one of the signal lines may be formed by its associated substrate.

[0018] The antenna radiator may be associated with a third substrate separate from the first substrate and / or the second substrate. In one example, the antenna radiator is arranged on its associated substrate. In another example, the antenna radiator is formed by its associated substrate. The antenna radiator may comprise one or more (e.g., two) dipole radiators. The antenna radiator may be configured as a dualpolarization radiator. The antenna radiator may be associated with two or four (e.g., symmetric) feed lines.

[0019] In one example, the associated substrate may comprise a dielectric material. The associated substrate may be configured as a substrate of a printed circuit board, PCB. In these cases, a signal line associated with the substrate may be arranged on the substrate, for example as a conductive track. In one variant, the associated substrate does not comprise a ground layer and / or the signal line associated with the substrate is not arranged in parallel to a ground layer.

[0020] In another example, the associated substrate is made of (e.g., sheet) metal. In this case, a signal line associated with the substrate may be made from the sheet metal. A substrate may form the signal line(s) associated with said substrate.

[0021] At least two of the capacitive coupling bridges may be mirror-symmetric with respect to one another. For example, (e.g., the) at least two capacitive coupling bridges are mirror-symmetric relative to the second substrate.

[0022] The first signal line and the second signal line may form part of a balanced feed for the antenna radiator. For example, two or four of the signal line sets form a balanced feed for the antenna radiator. The first signal line, the capacitive coupling bridge and the second signal line may form a first (e.g., symmetrical) feed line for the antenna radiator. The first feed line may be part of a balanced feed for the antenna radiator. The balanced feed may comprise or consist of the (e.g., symmetrical) first feed line and a (e.g., symmetrical) second feed line. The (e.g., symmetrical) second feed line may be formed similarly to the (e.g., symmetrical) first feed line by a respective first signal line, capacitive coupling bridge and second signal line.

[0023] The capacitive coupling bridge may be configured to act as a bandpass filter for signals transmitted between the first signal line and the second signal line via the capacitive coupling bridge. The bandpass filter may have a passband comprising an operating frequency of the antenna radiator.

[0024] The system may further comprise at least one attachment arrangement selected from (i) a first attachment arrangement configured to attach the first coupling portion relative to the first signal line portion and (ii) a second attachment arrangement configured to attach the second coupling portion relative to the second signal line portion.

[0025] The at least one attachment arrangement may comprise at least one fastening element. The at least one attachment arrangement may comprise multiple fastening elements that are spaced apart from one another, for example in a longitudinal direction (e.g., along the first axis or the second axis) of the coupling portion attached by the at least one attachment arrangement.

[0026] For example, one or more of the at least one fastening element extend through the second substrate and are configured to attach the second coupling portions of the capacitive coupling bridges associated with (e.g., the) at least two of the second signal lines relative to the second signal line portions of the at least two of the second signal lines. For example, one or more of the at least one fastening element extend through the first substrate and are configured to attach the first coupling portions of the capacitive coupling bridges associated with at least two of the first signal lines relative to the first signal line portions of the at least two of the first signal lines.

[0027] The capacitive coupling bridge may comprise at least one strip-shaped section selected from (i) a first strip-shaped section forming at least a part of the first coupling portion and (ii) a second strip-shaped section forming at least a part of the second coupling portion.

[0028] The at least one strip-shaped section may have a first width and the capacitive coupling bridge may comprise at least one fastening element reception section adjacent to the at least one strip-shaped section and having a second width larger than the first width.

[0029] The capacitive coupling bridge may comprise one or more through-holes for (e.g., the) fastening elements. Each of one or more of the at least one fastening element reception section may be formed around (e.g., a different) one of the one or more through-holes. In other words, a through-hole may be formed in the fastening element reception section.

[0030] The system may further comprise a first insulating layer arranged between the first signal line portion and the first coupling portion. The system may further comprise a second insulating layer arranged between the second signal line portion and the second coupling portion. At least one of the first insulating layer and the second insulating layer may be a foil or a coating.

[0031] For example, a width of the first insulating layer is larger than a width of the first signal line portion and / or a width of the first coupling portion. Alternatively, or in addition, a width of the second insulating layer may be larger than a width of the second signal line portion and / or a width of the second coupling portion.

[0032] At least one of the first insulating layer and the second insulating layer may comprise Polytetrafluoroethylene, PTFE. At least one of the first insulating layer and the second insulating layer may be a PTFE foil. A (e.g., homogeneous) thickness of at least one of the first insulating layer and the second insulating layer may be below 150 pm, below 100pm or below 80pm.

[0033] According to a second aspect, an antenna system is provided. The antenna system comprises the capacitive coupling system according to the first aspect. The antenna system further comprises the antenna radiator. The antenna radiator is connected with the second signal line of the capacitive coupling system. The antenna radiator may comprise a plurality of dipole arms, each of which is connected to a separate second signal line of the capacitive coupling system. The capacitive coupling system may provide a separate balanced feed for each dipole of the antenna radiator. The antenna radiator may be configured as a dual-polarization radiator comprising two dipoles.

[0034] According to a third aspect, a multi-antenna system is provided. The multi-antenna system comprises a plurality of antenna systems according to the second aspect. The antenna radiators of the plurality of antenna systems are arranged to form an antenna array. The feedlines of the plurality of antenna systems may be part of a feed network for the antenna array.

[0035] SHORT DESCRIPTION OF THE FIGURES

[0036] Examples in accordance with the technique disclosed herein are explained below with reference to the figures, wherein:

[0037] Figs. 1-3 schematically illustrate a first example of a capacitive coupling system in accordance with the present disclosure;

[0038] Fig. 4 schematically illustrates a second example of a capacitive coupling system in accordance with the present disclosure;

[0039] Fig. 5 illustrates an example of a capacitive coupling bridge in accordance with the present disclosure;

[0040] Fig. 6 illustrates the frequency behaviour of the capacitive coupling bridge of Fig. 5;

[0041] Fig. 7 illustrates a third example of a capacitive coupling system in accordance with the present disclosure;

[0042] Fig. 8 illustrates a fourth example of a capacitive coupling system in accordance with the present disclosure;

[0043] Fig. 9 illustrates a first example of an antenna system in accordance with the present disclosure; and

[0044] Fig. 10 illustrates a second example of an antenna system in accordance with the present disclosure.

[0045] DETAILED DESCRIPTION

[0046] Unless indicated otherwise, the reference signs used in the following denote the same or similar structural or functional features. In case an example shows more than one instance of a given entity, which entity is denoted with reference numeral "X", these instances may be referred to either as "X", or as "X- / / ' with n indicating the particular instance.

[0047] Figs. 1-3 schematically illustrate a first example of a capacitive coupling system 100 in accordance with the present disclosure. The system 100 comprises two signal line sets. A first set of the signal line sets consists of a first signal line 2-1 having a first signal line portion 4-1, and a second signal line 6-1 having a second signal line portion 8-1. A second set of the signal line sets consists of first signal line 2-2 having a first signal line portion 4-2, and a second signal line 6-2 having a second signal line portion 8-2. The second signal lines 6-1, 6-2 are configured to be connected with an antenna radiator (not shown in Figs. 1-3), whereas the first signal lines may be connected to a feed network (also not shown in Figs. 1-3). The first feed lines 2-1, 2- 2 are electrically isolated from the second feed lines 6-1, 6-2.

[0048] Each of the signal line sets is associated with a capacitive coupling bridge 10-1, 10-2. Each bridge 10-1, 10-2 is formed of (e.g., stamped and / or bent) sheet metal, for example stainless steel, and has a first coupling portion 12-1, 12-2 and a second coupling portion 14-1, 14-2. Each signal line set, together with the associated coupling bridge 10-1, 10-2, can form a separate (e.g., symmetrical) feed line for the antenna radiator. For example, the system 100 may provide a balanced feed for the antenna radiator that consists of two (e.g., symmetrical) feed lines formed by the respective signal line sets.

[0049] Each coupling bridge 10-1, 10-2 is configured to arrange the associated second signal line 6-1, 6-2 in a predefined pose relative to the associated first signal line 2-1, 2-2. The capacitive coupling bridge 10-1 is configured to provide a first capacitive coupling between the first coupling portion 12-1 and the first signal line portion 4-1, and to provide a second capacitive coupling between the second coupling portion 14- 1 and the second signal line portion 8-1 to capacitively couple the first signal line 2-1 to the second signal line 6-1. Similarly, the capacitive coupling bridge 10-2 is configured to provide a first capacitive coupling between the first coupling portion 12-2 and the first signal line portion 4-2, and to provide a second capacitive coupling between the second coupling portion 14-2 and the second signal line portion 8-2 to capacitively couple the first signal line 2-2 to the second signal line 6-2. In order to provide an efficient capacitive coupling, the signal line portion 4, 8 and the coupling portion 12, 14 forming a respective coupling are arranged in an overlapping manner. One may say that the signal line portion 4, 8 and the coupling portion 12, 14 forming a respective coupling are stacked on top of one another. For example, the coupling portion 12-1 overlaps the signal line portion 4-1 (e.g., in a top view onto a plane x-z parallel to which the two portions are arranged) and forms a higher layer of the stack compared with the signal line portion 4-1.

[0050] The bridges 10-1, 10-2 are electrically isolated from the first and second feed lines 2- 1, 2-2, 6-1, 6-2 by first insulating layers 15-1, 15-2 and second insulating layers 17- 1, 17-2. Such an insulating layer may have a high specific electrical resistance (e.g., above 1010Q cm, above 1020Q cm or above 1023Q cm). Such an insulating layer may be a foil (e.g., a PTFE foil) or a coating and is configured to prevent current from flowing between the adjacent signal line portion 4, 8 and the adjacent coupling portion 12, 14 during operation of the antenna radiator.

[0051] For high capacitive coupling, thicknesses of the isolating layers 15, 17 may be selected to be rather small (e.g., below 200pm, below 150pm, below 100pm or below 80pm). The isolation layers 15, 17 may each have a spatially constant thickness. The material of the respective isolating layer 15, 17 may be chosen such that its dielectrical losses are as low as possible, and such that it has low fluctuations of thickness and low fluctuations of dielectrical properties. The isolating layer may also be temperature stable (e.g., have a melting point above 100°C, above 200°C or above 300°C).

[0052] When using air as isolating layer, it may be difficult to align all the components of the stack relative to one another. Foils like Teflon® foil have proven to be a good choice, because such foils are available in very low thicknesses (e.g., in the range of 40 - 100pm) and the dielectrical losses of such foils are generally low (e.g., loss tangent in the range of 0.001 to 0.005). When using solder resist of a PCB as an isolating layer, one may reach an isolating layer thickness of 10-70 pm. Nevertheless, the dielectric losses of typical solder resist are quite high (e.g., loss tangent between 0.01 to 0.03).

[0053] An isolating (e.g., PTFE) foil 15, 17 may be sized to have a larger width compared to the capacitive coupling bridge 10 to prevent an electrical short circuit between the bridge 10 and the signal line(s) 2, 6 and / or other conductive materials arranged on a first or second substrate 16, 18. The insulating layers 15-1, 17-1 may have larger widths wl, w2 than the respective signal line portions 4-1, 8-1 with widths w3, w4, and optionally larger widths wl, w2 than the (e.g., coupling portions of the) bridge 10-1 (e.g., in a top view onto a plane x-z in which the insulating layer is arranged, see Fig. 2) with widths w5-w7. The same may apply to the insulating layers 15-2, 17- 2. Each insulating layer 15-1, 15-2, 17-1, 17-2 is sandwiched (e.g., in the y-direction) between a coupling portion and a signal line portion, and is thus part of the stack forming a respective coupling.

[0054] This arrangement allows for an electric feed signal to be fed from the first signal line 2 to the second signal line 6 via the respective bridge 10 using capacitive couplings instead of, for example, solder connections. Each bridge 10 can be said to fulfil a double function by not only transferring the signal between the first and second signal lines 2, 6, but by furthermore providing a mechanical attachment of the first signal lines 2 relative to the second signal lines 6.

[0055] In the example of Fig. 1, the first signal lines 2-1, 2-2 are conductive tracks arranged on opposite sides of first dielectric substrate 16. The first substrate and the first signal lines 2-1, 2-2 may be part of a printed circuit board. In a similar manner, the second signal lines 6-1, 6-2 are formed as conductive tracks on opposite surfaces of second dielectric substrate 18. In the illustrated example, neither the first substrate 16 nor the second substrate 18 comprises a ground layer interposed between the first signal lines 2-1, 2-2 or the second signal lines 6-1, 6-2.

[0056] The bridges 10-1, 10-2 are configured to arrange the first and second substrates 16, 18 in a predefined pose relative to one another. To this end, each bridge 10-1, 10-2 is attached to both substrates 16, 18 by way of attachment arrangements 20, 21 configured to attach the coupling portions 12, 14 relative to the overlapped signal line portions 4, 8. Each attachment arrangement 20-1, 20-2 comprises at least one fastening element, also referred to as attachment element herein. The fastening element may be a (e.g., non-conductive) rivet (e.g., made from plastic). The fastening element may have a high specific electrical resistance. In the illustrated example, fastening element 22 extends through a through-hole 23-1 in the bridge 10-1 and the first substrate 16 and attaches the bridge 10-1 to the substrate 16, and also extends through a through-hole 23-2 in the bridge 10-2 and attaches the bridge 10-2 to the substrate 16. Similarly, fastening element 24 extends through through- holes 25-1, 25-2 in bridges 10-1, 10-2 and the substrate 18, and attaches both bridges 10-1, 10-2 to the second substrate 18. The fastening elements 22, 24 also ensure that the coupling portion 12, 14, insulating layer 15, 17 and signal line portion 4, 8 of the individual coupling(s) remain in their stacked arrangement. In particular, a relative movement of these components in the x-direction, the y-direction and / or the z-direction can be prevented by the associated fastening element 22, 24. Fig. 4 schematically illustrates a second example of a capacitive coupling system 200 in accordance with the present disclosure, to demonstrate that the capacitive coupling system disclosed herein is not limited to the example shown in Figs. 1-3 but can be modified in various ways. For example, the first signal line 2-1 can be covered entirely with insulating layer 15, not only in the region of the first capacitive coupling. In this case, the layer 15 may be a (e.g., polymer) coating. It can also be seen in Fig. 2 that the multiple first signal lines 2 in accordance with the present disclosure may be arranged on a same side of the first substrate 16, or that only one first signal line 2 may be provided.

[0057] The capacitive coupling system may not comprise the second dielectric substrate 18. Rather, the second signal line 6 can be formed as a self-supporting (e.g., freestanding) element, for example from sheet metal. In this case, one may say that the second signal line 6 is not arranged on its associated substrate, but rather formed by its associated substrate. The first signal line 2-1 may similarly be formed by its associated substrate. As another example, a signal line (e.g., the second signal line 6) formed by its associated substrate may be entirely coated (e.g., on all sides) with the insulating layer (e.g., the insulating layer 17). Further modifications of the capacitive coupling system in accordance with the present disclosure are possible.

[0058] Fig. 5 illustrates an example of a capacitive coupling bridge 10 in accordance with the present disclosure. This bridge 10 may be used as the coupling bridge 10 in a capacitive coupling system in accordance with the present disclosure, for example in the system 100, 200, 300 or 400.

[0059] In the illustrated example, both the first coupling portion 12 and the second coupling portion 14 of the bridge 10 are planar. The coupling portions 12, 14 are connected to each other by a bent portion 26 of the sheet metal forming the capacitive coupling bridge 10. In this manner, the first coupling portion 12 lies parallel to a first plane 28 whereas the second coupling portion 14 lies parallel to a different second plane 30. In the illustrated example, the two planes 28, 30 are perpendicular to one another, although other relative angles between the two planes 28, 30 are also possible. The first coupling portion 12 extends longitudinally along a first axis 32, the second coupling portion 14 extends longitudinally along a different second axis 34. In the illustrated example, the first axis 32 is parallel to the second axis 34 and the first coupling portion 12 is offset from the second coupling portion 14 along at least one of the first axis 32 and the second axis 34, although the present disclosure is not limited thereto. This allows coupling first and second signal lines 2, 6 using the bridge 10, even if the signal lines 2, 6 lie in different planes and / or are offset from one another.

[0060] The capacitive coupling bridge 10 shown in Fig. 5 comprises a first strip-shaped section 36 forming the first coupling portion 12 and a second strip-shaped 38 section forming the second coupling portion 14. The strip-shaped section 36 has width w5 and the strip-shaped section 38 has width w7. In the illustrated example, w5 differs from w8, in particular w5 > w8.

[0061] The capacitive coupling bridge 10 comprises multiple fastening element reception sections 40, 42 adjacent to the strip-shaped section 38 and having a width w8 > w7. Each fastening element reception section 40, 42 is formed around a respective through-hole 25 configured to receive a respective fastening element 24. It is also possible to provide one or more fastening element reception sections adjacent or at to the strip-shaped section 36. As apparent from the shape of the strip-shaped section 36 shown in Fig. 5, such wider fastening element reception sections 40, 42 need not be provided at one or both strip-shaped sections 36, 38, but instead, the through-holes 23, 25 may simply be arranged within the strip-shaped section(s) 36, 38. In this case, the bridge 10 can have a constant width w5, w7 on one or both ends.

[0062] This capacitive coupling bridge 10 may be configured to act as a bandpass filter for signals transmitted between the first signal line 2-1, 2-2 and the second signal line 6- 1, 6-2 via the capacitive coupling bridge 10. In this case, the bandpass filter has a passband that comprises an operating frequency of the antenna radiator.

[0063] Fig. 6 illustrates the frequency behaviour of the capacitive coupling bridge 10 of Fig. 5 as a diagram of the parameter SI, 2 (also referred to as S2i) over frequency. The frequency behaviour shown in Fig. 6 was obtained as a result of a simulation of the frequency behaviour of the bridge 10 as part of a third exemplary capacitive coupling system 300 as shown in Fig. 7. For the simulation, the isolating layer was selected to be made of a solder resist with a thickness of 40pm having a dielectric constant of 4.4. The loss tangent of the solder resist was assumed to be 0.03. The area of the coupling portions 12, 14 overlapping the signal line portions 4, 8 was set to 12 x 5 mm. In this example, the bridge 10 has a passband of 700-960 MHz across which S2,l > -0.175 dB. Fig. 7 shows illustrates a third example of a capacitive coupling system 300 in accordance with the present disclosure. In this case, the bridges 10-1, 10-2 each comprise fastening element reception sections 40, 42 adjacent to the respective strip-shaped section 38, and comprises through-holes 23-1, 23-2 (not shown) formed in the strip-shaped sections 36-1, 36-2. Rivets 22, 24 made from plastic fix the first substrate 16 to the second substrate 18 via the bridges 10. The rivets 24 are spaced apart from one another along the second axis 34.

[0064] As shown in Fig. 7, the first signal lines 2-1, 2-2 may both arranged one a first surface of the first substrate 16 in the first plane 28 whereas the second signal lines 6-1, 6-2 may be arranged (e.g., in parallel) on opposite sides of the second substrate 18 aligned with the second plane 30. The first substrate 16 may comprise a ground plane (not visible in Fig. 7) that forms its second surface or embedded within the dielectric material thereof, whereas the second substrate 18 may not comprise a ground plane. The second signal lines may be mirror-symmetric to one another (e.g., with respect to the second substrate 18 and / or the second plane 30). The capacitive coupling bridges 10-1, 10-2 are for example mirror-symmetric with respect to one another relative to the second substrate and / or the second plane 30. The first signal lines 2-1, 2-2 each end with the signal line portions 4-1, 4-2 overlapping the first coupling portions of the coupling bridges 10-1, 10-2. In Fig. 7, the substrate 16 in the area of these capacitive couplings is hidden below the isolating layer 15. This arrangement may be referred to as a symmetric feed.

[0065] Fig. 8 illustrates a fourth example of a capacitive coupling system 400 in accordance with the present disclosure. In this case, a fastening element reception section 43 is also arranged at the strip-shaped section 36 of each bridge 10-1, 10-2. Furthermore, each bridge 10-1, 10-2 is flipped by 180° relative to the first substrate 16 when compared with the arrangement of Fig. 7.

[0066] That is, the bridge 10 disclosed herein may be arranged such that a top surface of the strip-shaped section 36 is in contact with the isolating layer 15 or a bottom surface of the strip-shaped section 36 is in contact with the isolating layer 15. Similarly, the bridge 10 may be arranged such that a top surface of the strip-shaped section 38 is in contact with the isolating layer 17 or a bottom surface of the stripshaped section 38 is in contact with the isolating layer 17. This shows that the bridge 10 disclosed herein is versatile and allows capacitively connecting first signal lines 2- 1, 2-2 arranged on a top surface of the first substrate with second signal lines 6-4, 6- 2 that may be located (e.g., in the y-direction) beneath or above the top surface of the first substrate 16, for example.

[0067] Fig. 9 illustrates a first example of an antenna system 1000 in accordance with the present disclosure. The antenna system 1000 comprises the capacitive coupling system 400 and further comprises an antenna radiator 500. In this example, the system 400 comprises two pairs of first signal lines 2 with each pair being arranged in common plane (e.g., on a separate PCB) parallel to the common plane of the other pair. The system 400 also comprises two pairs of second signal lines 6 with each pair being arranged on a different surface of the second substrate 18. Each first signal line 2 is capacitively coupled to an associated second signal line 6 via a respective bridge 10. Thus, a total of four bridges 10 attach the second substrate 18 relative to the substrate(s) on which the first signal lines 2 are arranged.

[0068] In the example of Fig. 9, four feed lines are provided for the antenna radiator 500, each formed by a first signal line 2, a bridge 10 and a second signal line 6. The four feed lines may be configured as two separate balanced feeds, each balanced feed consisting of two (e.g., symmetrical) feed lines (e.g., arranged on opposite surfaces of the substrate 16 and / or 18). In this case, the second substrate 18 may be ground- free. Each balanced feed may be associated with a different dipole radiator 502, 504 of the antenna radiator 500. The dipole radiator 502 comprises dipole arms 506, 508 and the dipole radiator 504 comprises dipole arms 510, 512. Each of the second signal lines 6 may be connected to a different dipole arm 506, 508, 510, 512. In this manner, the antenna radiator 500, configured as a dual-polarization radiator, can be fed with feed signals via balanced feeds.

[0069] The antenna radiator 500 may be associated with a third substrate 514. For example, the arms 506-512 may be arranged on the third substrate or formed by the third substrate. The third substrate 514 may be attached to the second substrate 18 (e.g., slotted into the second substrate 18 or vice versa). Thus, one may say that the bridges 10 can not only provide a reliable feeding of the antenna radiator 500 with feed signals having desired frequencies, but also may hold the antenna radiator 500 in a desired pose.

[0070] Fig. 10 illustrates a second example of an antenna system 2000 in accordance with the present disclosure. In this example, two feed lines are formed by two first signal lines 2 arranged on the same, first surface of the first substrate 16, by capacitive coupling bridges 10-1, 10-2 and by second signal lines 6. These two feed lines may feed two different polarizations of the radiator.. In difference to the example of Fig. 9, the second signal lines 6 are not arranged on opposite surfaces on the second substrate 18, but rather spaced apart from one another (e.g., at least partially in parallel) and on a same, first surface of the second substrate 18. In this example, the antenna system 2000 further comprises a ground layer 103 associated with the second signal lines 6. This ground layer 103 may be arranged in parallel with the second substrate 18 (e.g., on a second surface thereof or embedded therein). The antenna system 2000 may comprise an additional capacitive coupling bridge 101 constructed in a similar manner as the bridges 10 described herein, but used to capacitively couple the ground layer 103 to a ground connection 105 associated with the first substrate 16. The bridge 101 may share one or more fastening elements (e.g., 22, 24) with the bridge 10-1 and / or 10-2. The ground connection 105 may be another ground layer or a conductive track arranged on or within the first substrate 16 and (e.g., configured to be) electrically connected to ground. It is also possible to use such a ground-connecting bridge 10 in the antenna system 1000 or the capacitive coupling systems 100-400.

[0071] The antenna system 1000, 2000 may be modified by using variations of the capacitive coupling system 400 instead, for example the capacitive coupling system 100, 200 or 300. It is also possible to use different types of bridges 10 as those shown in Fig. 9, and / or to use different types of bridges 10 as part of one and the same capacitive coupling system. More generally speaking, features of the capacitive coupling systems described herein may be combined or modified. For example, the shape of the bridge shown in Fig. 5 may be applied to the example shown in Fig. 4, or the shape of the bridges shown in Figs. 1-4 may be used in the systems 300, 400. Various other modifications and advantages of the technique disclose herein may become apparent to those skilled in the art.

Claims

CLAIMS1. A capacitive coupling system (100; 200; 300; 400) for an antenna radiator, the system (100; 200; 300; 400) comprising: a first signal line (2) having a first signal line portion (4); a second signal line (6) having a second signal line portion (8) and configured to be connected with an antenna radiator (500); and a capacitive coupling bridge (10) formed of sheet metal and having a first and a second coupling portion (12; 14), the coupling bridge (10) being configured to arrange the second signal line (6) in a predefined pose relative to the first signal line (2), the capacitive coupling bridge (10) further configured to provide a first capacitive coupling between the first coupling portion (12) and the first signal line portion (4), and to provide a second capacitive coupling between the second coupling portion (14) and the second signal line portion (8) to capacitively couple the first signal line (2) to the second signal line (6).

2. The system (100; 200; 300; 400) of claim 1, wherein the first signal line (2) is arranged in a first plane (28) and the second signal line (6) is arranged in a second plane (30) different from the first plane.

3. The system (100; 200; 300; 400) of claim 2, wherein the first plane (28) is oblique or perpendicular to the second plane (30).

4. The system (100; 200; 300; 400) of any one of claims 1 to 3, wherein at least one of the first coupling portion (12) and the second coupling portion (14) is planar.

5. The system (100; 200; 300; 400) of claim 4, wherein the first coupling portion (12) and the second coupling portion (14) are each planar and connected to one another via a bent portion (26) of the sheet metal forming the capacitive coupling bridge (10).

6. The system (100; 200; 300; 400) of any one of claims 1 to 5, wherein the first coupling portion (12) extends longitudinally along a first axis (32) and the second coupling portion (14) extends longitudinally along a second axis (34), wherein the first axis (32) is parallel to the second axis (34) and / or the first coupling portion (12)is offset from the second coupling portion (14) along at least one of the first axis (32) and the second axis (34).

7. The system (100; 200; 300; 400) of any one of claims 1 to 6, wherein the first signal line (2) is associated with a first substrate (16) and the second signal line (6) is associated with a second substrate separate (18) from the first substrate (16), wherein the capacitive coupling bridge (10) is configured to fix the first substrate (16) relative to the second substrate (18).

8. The system (100; 200; 300; 400) of any one of claims 1 to 7 comprising multiple signal line sets, each signal line set consisting of a first signal line (2) and a second signal line (6), the system (100; 200; 300; 400) comprising a separate capacitive coupling bridge (10) for each of the signal line sets, wherein the first signal lines (2) are associated with a first substrate (16) and the second signal lines (6) are associated with a second substrate (18) separate from the first substrate (16).

9. The system (100; 200; 300; 400) of claim 7 or 8, wherein at least one of the signal lines (2, 6) is arranged on its associated substrate (16, 18).

10. The system (100; 200; 300; 400) of claims 8 and 9, wherein at least two of the second signal lines (6) are arranged on opposite surfaces of the second substrate (18) and / or at least two of the first signal lines (2) are arranged on a same surface of the first substrate (16).

11. The system (100; 200; 300; 400) of any one of claims 7 to 10, wherein the second substrate is ground-free.

12. The system (100; 200; 300; 400) of any one of claims 7 to 11, wherein at least one of the signal lines (2, 6) is formed by its associated substrate (16, 18).

13. The system (100; 200; 300; 400) of any one of claims 7 to 12, wherein the antenna radiator (500) is associated with a third substrate separate (514) from the first substrate (16) and / or the second substrate (18).

14. The system (100; 200; 300; 400) of claim 13, wherein the antenna radiator (500) is arranged on its associated substrate (514).

15. The system (100; 200; 300; 400) of claim 13, wherein the antenna radiator (500) is formed by its associated substrate (514).

16. The system (100; 200; 300; 400) of at least claim 9 or at least claim 14, wherein the associated substrate (16; 18; 514) comprises a dielectric material and / or is configured as a substrate of a printed circuit board, PCB.

17. The system (100; 200; 300; 400) of at least claim 12 or at least claim 15, wherein the associated substrate (16; 18; 514) is made of sheet metal.

18. The system (100; 200; 300; 400) of at least claim 8, wherein at least two of the capacitive coupling bridges (10) are mirror-symmetric with respect to one another.

19. The system (100; 200; 300; 400) of claim 18, wherein the at least two capacitive coupling bridges (10) are mirror-symmetric relative to the second substrate (18).

20. The system (100; 200; 300; 400) of any one of claims 1 to 19, wherein the first signal line (2) and the second signal line (6) form part of a balanced feed for the antenna radiator (500).

21. The system (100; 200; 300; 400) of at least claim 8, wherein two or four of the signal line sets form a balanced feed for the antenna radiator (500).

22. The system (100; 200; 300; 400) of any one of claims 1 to 21, wherein the capacitive coupling bridge (10) is configured to act as a bandpass filter for signals transmitted between the first signal line (2) and the second signal line (6) via the capacitive coupling bridge (10), the bandpass filter having a passband comprising an operating frequency of the antenna radiator (500).

23. The system (100; 200; 300; 400) of any one of claims 1 to 22, further comprising at least one attachment arrangement (20; 21) selected from a first attachment arrangement (20) configured to attach the first coupling portion (12) relative to the first signal line portion (4) and a second attachment arrangement (21) configured to attach the second coupling portion (14) relative to the second signal line portion (8), wherein the at least one attachment arrangement (21; 22) comprises at least one fastening element (22; 24).

24. The system (100; 200; 300; 400) of claim 23, wherein the at least one attachment arrangement (21) comprises multiple fastening elements (24) that are spaced apart from one another in a longitudinal direction of the coupling portion (14) attached by the at least one attachment arrangement (21).

25. The system (100; 200; 300; 400) of claim 23 or 24, and at least claim 10, wherein one or more of the at least one fastening element (22; 24) extend through the second substrate (18) and are configured to attach the second coupling portions (14) of the capacitive coupling bridges (10) associated with the at least two of the second signal lines (6) relative to the second signal line portions (8) of the at least two of the second signal lines (6).

26. The system (100; 200; 300; 400) of any one of claims 1 to 25, wherein the capacitive coupling bridge (10) comprises at least one strip-shaped section (36; 38) selected from a first strip-shaped section (36) forming at least a part of the first coupling portion (12) and a second strip-shaped section (38) forming at least a part of the second coupling portion (14).

27. The system (100; 200; 300; 400) of claim 26, wherein the at least one stripshaped section (38) has a first width (w7) and the capacitive coupling bridge (10) comprises at least one fastening element reception section (40; 42) adjacent to the at least one strip-shaped section (38) and having a second width (w8) larger than the first width (w7).

28. The system (100; 200; 300; 400) of any one of claims 1 to 27, wherein the capacitive coupling bridge (10) comprises one or more through-holes (23, 25) for fastening elements (22, 24).

29. The system (100; 200; 300; 400) of claims 27 and 28, wherein each of one or more of the at least one fastening element reception section (40; 42; 43) is formed around one of the one or more through-holes (23, 25).

30. The system (100; 200; 300; 400) of any one of claims 1 to 29, further comprising: a first insulating layer (15) arranged between the first signal line portion (4) and the first coupling portion (12); anda second insulating layer (17) arranged between the second signal line portion (8) and the second coupling portion (14), wherein at least one of the first insulating layer (15) and the second insulating layer (17) is a foil or a coating.

31. The system (100; 200; 300; 400) of claim 30, wherein{i} a width (w3) of the first insulating layer (15) is larger than a width (w2) of the first signal line portion (4) and / or a width (w5) of the first coupling portion (12), and / or{ii} a width (w4) of the second insulating layer (17) is larger than a width (w2) of the second signal line portion (8) and / or a width (w7) of the second coupling portion (14).

32. The system (100; 200; 300; 400) of claim 30 or 31, wherein at least one of the first insulating layer (15) and the second insulating layer (17) comprises Polytetrafluoroethylene, PTFE.

33. An antenna system (1000; 2000) comprising: the capacitive coupling system (100; 200; 300; 400) according to any one of claims 1 to 32; and the antenna radiator (500) connected with the second signal line (6).

34. A multi-antenna system comprising: a plurality of antenna systems (1000; 2000) according to claim 33, wherein the antenna radiators (500) of the plurality of antenna systems(1000; 2000) are arranged to form an antenna array.

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